There was a field grade 325 along with the Sporting but never in a upland version.
From Bruce Buck ( Shotgun Report ):
Well, yes, there may be a difference in that all the 425s have enlarged bores, while many of the 325s did not. Also, some of the earlier 325s built to English specifications had lighter barrels and are much sought after here in the US.
What that tells me is the 325 series if tubed would have invector chokes . as I know the invecter plus is designed for the back bored barrels .




























